Package: - It’s a collection of control flow tasks. It’s the unit of work which is retrieved, executed and saved.

Client: – SSIS system can be connected via various
clients like SSIS designer which comes with BI IDE, custom applications,
SSIS wizard etc. These clients use the object model to communicate with
the SSIS system.

Connection manager and data sources: - They help us to define connection objects with data sources which can be reused in data flow task.

DTSX files, MSDB and Integration service: - The
complete package can be stored in DTSX files or database. These packages
can later be connected and invoked using integration service which runs
at the background as windows services.

Event handlers: - When you run any SSIS package you
would like to trap various events like
OnError,OnPostExecute,OnPreExecuteetc to run certain logic like logging
in to database , send emails etc.